Consumption of fruit and vegetable juices has greatly increased as better quality, better tasting and higher purity juice products have been developed. The challenge of producing beverages acceptable to a broad range of consumers involves balancing the flavor, aroma, appearance and satisfactory mouthfeel. The level of sugars and sweetness affect these characteristics.
As consumers become more calorie conscious, they become concerned about their daily sugar consumption. A good tasting beverage which is low in both calories and sugars is desirable. Lower calorie juices have been made by removing some of the sugars and adding artificial sweeteners or by diluting the juice. Consumers are also concerned about their intake of artificial sweeteners.
Some plants of the Cucurbitaceae family, found mostly in southern Asia, produce unique intensely sweet fruits. These fruits have a characteristic intense sweetness due to the presence of terpene glycosides, natural materials which can provide the sweetness of natural sugar with negligible calories and without the need for artificial sweeteners.
The best known fruit in this family, called Luo Han Guo, is produced by the plant S. grosvenorii found in southern China. The fresh fruit has an earthy, beany, vegetable flavor. Some fruits also have bitter tastes. The fresh fruits degrade on standing within a few weeks. These fruits contain very sweet terpene glycosides called mogrosides. Mogrosides IV and V, 11-oxo-mogroside V, and siamenoside I have been identified and characterized chemically as the very sweet components of the geuus Siraitia. See for example, Matsumoto, et al., Chem. Pharm. Bull., 38 (7), 2030-2032 (1990).
Traditionally these fruits are slowly dried in ovens and stored in the dry state until used. The drying process preserves the fruit and removes most of the objectionable flavor of the fresh fruit. The drying also causes the formation of bitter, astringent and some browned flavors. These flavors restrict the use of the dried fruits and dried fruit extracts to the preparation of dilute teas and soups and products to which sugar, honey and the like are added.
Luo Han Guo, the most common Cucurbitaceae fruit, is seldom used fresh due to the problems of storing it, its unattractive vegetable flavor and its tendency to form off-flavors. The juice of Luo Han Guo fruit has a natural pH of about 6 and it contains sugars which can brown and ferment. The pectin eventually gels on standing.
Juices can be concentrated or dried by evaporation processes which involve heating juice sometimes under vacuum. Hydrolysis and/or oxidation of components of the juice can occur. Lipids can be oxidized and amino acids and sugars can undergo browning reactions during evaporation. Such degradation products can cause off-flavors in the concentrated juice.
It is generally recognized that evaporation concentration processes are useful and fairly effective, but there is a significant loss of aroma and flavor compounds which occurs. In the case of juices from the Cucurbitaceae family, the loss of certain aromas may be desirable.
It is an object of the present invention to provide a process for producing a very sweet fruit juice and concentrate made from very sweet juices of the Cucurbitaceae family, including Luo Han Guo juice. It is also an object to produce this juice so that it does not contain objectionable off-flavors, and does not reform substantial quantities of off-flavors on storage.
It is a further object of this invention to produce a juice, and in particular, a fruit juice, which is lower in sugar and calories by blending the very sweet Cucurbitaceae juices with other fruit juices.
These and other objects of this invention will become apparent from the description of the invention hereinafter.